facts or events which are contrary to a cherished conviction, and remember only those which support it, is responsible for the existence of this and many other like beliefs.

So firm is the fallacy as to explosions causing rain that in the year 1911 a member of the House of Commons asked the First Lord of the Admiralty in Parliament whether he would arrange for the fleet to carry out their heavy gun-firing practice round the coast at some other period of the year than in the middle of the harvest-time, when the resulting heavy rain may cause serious loss to the farming community." The reply was that "there is no evidence that the firing causes heavy rain," but this only meets belief with denial. Though the argument is not strictly scientific, perhaps the most convincing form of reply to those who profess to believe, or do believe, in the efficacy of gunfiring to produce rain, is to point out that the firing of big guns is carried on at Shoeburyness more frequently than at any other point on the coast, yet the mean rainfall at Shoeburyness, and on the coast of Essex generally, is the lowest in the British Isles.

It is commonly believed that during severe thunderstorms a bolt is sometimes discharged from the clouds and reaches the earth as a solid mass of stone or metal. There is, however, not a particle of material evidence in support of this belief. No thunderbolt originating in the clouds has ever been found, and none exists, whatever conviction may be held to the contrary. What are mistaken for thunderbolts as popularly understood are peculiar mineral objects, meteorites, or particles of soil or rock which have been fused by lightning striking the earth through them.

Masses of a metallic or stony nature do fall from the sky occasionally, but they have nothing to do with

thunderstorms, and really reach the earth from outer space. In its annual journey around the sun the earth now and then encounters stray fragments of cosmic matter, and draws them toward itself by the force of gravitation. When the mass reaches the earth's atmosphere, friction against the air makes it white hot, and like a moth flying into a flame it is consumed, the streak of light thus produced being a shooting star or meteor. Sometimes the piece of cosmic material is so large that it is not completely consumed as it traverses the atmosphere; and in this case it reaches the earth as a solid mass- a meteorite which may weigh a few ounces or several tons. Many of these meteorites are preserved in our museums, but though they may make a noise or a series of explosions as they hurl themselves toward the earth, they are not connected in any way with thunderstorms, and cannot correctly be termed thunderbolts.

Other objects often mistaken for thunderbolts are known to geologists as fulgurites, and are produced by the fusion of grains of loose sand by a lightning discharge. At the mouth of the river Irt, in Cumberland, fulgurites have been found extending to a depth of forty feet in the sand, and a fulgurite found in a sandy stratum at Macclesfield reached to a depth of twenty-two feet. It is perhaps natural to conclude that tubes or patches of fused rock, found after lightning has been seen to strike the earth in a place where only loose sand could be seen, actually came from the clouds, but here again the view that "seeing is believing " leads to an erroneous conclusion.

In the absence of any precise knowledge of the nature of globular or ball lightning, it may be undesirable to assert that nothing solid can come from a thunder

cloud; nevertheless, it can be stated with confidence that no so-called thunderbolt has ever proved to be one, so that the possessor of a true specimen would have an object of unique value and interest. In the absence of such a specimen, it is permissible to state that no thunderstorm has ever discharged a thunderbolt which was afterwards picked up and is preserved in a museum, or among a private collection of curiosities.

Uncritical observation and hasty conclusion are responsible for the reports of the occurence of living frogs and toads enclosed in blocks of coal or other hard rock many feet below the surface of the ground. A stone is being broken by a quarryman, a frog is seen hopping about close to the place, and forthwith the lively imagination of the labourer persuades him that he has seen it actually come out of a cavity in the rock. Dean Buckland made experiments for the purpose of ascertaining how long frogs and toads could live shut up in cavities of stone and excluded from air and food, with the result that most of them were dead within a year, and none survived more than two years. Yet frogs are alleged to have been found enclosed in rocks which, geology teaches, were deposited under water millions of years ago, and afterwards subjected to a pressure which has crushed all the fossils contained in them as flat as paper. If geology is right, the frog stories are utterly incredible. Or, as a distinguished geologist once said, the blow of the hammer that disclosed a live frog inside a block of stone without an opening would at the same time destroy not only geology but the whole fabric of natural science.

Critical examination of evidence, and cautious consideration of conclusions, are characteristic attributes of a scientific mind. There is a tendency in the present